U.S. Pat. No. 4,663,377, the teachings of which are incorporated herein by reference, is directed to dispersible polyisocyanate compositions suitable for curing aqueous adhesives, including aqueous polyurethane dispersions. In this patent, polyisocyanates are emulsified using a surfactant which is preferably the reaction product of the polyisocyanate and a polyether. The major portion of the monomers used to form the polyether comprises ethylene oxide. Ethylene oxide units, as opposed to propylene oxide units (or higher alkyl oxide units), are used because they are known to promote water-compatibility.
The present invention is directed to curatives for aqueous adhesives, particularly dispersed polyurethane adhesives, which provide enhanced water-resistance, e.g., humidity resistance, to the cured adhesive. The curative is particularly suitable when used in a laminate adhesives, i.e., an adhesive to bond polymer and/or metal layers together.